Abstract

The optical feedback properties of laser diodes have been classified into five regions of behaviour, denoted regimes I to V respectively.¹ In the present work we report the first detailed investigation of the transition from regime V (stable AR coated external cavity operation) and IV (coherence collapse). The relative intensity noise (RIN) behaviour of the laser output is investigated by varying the external mirror reflectivity and the bias current. As anticipated, the intensity noise increases as the current decreases due to the increased contribution from the spontaneous emission as the laser approaches threshold. However, for any bias current there is a value of the external reflectivity below which there is a sudden increase in RIN. This behaviour has previously been identified as the transition between regimes V and IV.^2,3

© 1994 IEEE